http://www.torhead.com/skill-calc#801GRGb00bZZbIbbdGbM.1
I start my spec idea on the notion that +30% crit dmg is too much to pass up in assault for anyone with Eliminator 4 pc set bonus (+15% crit chance on HiB]. For me, this means I need to set my builds with 22 in Assault. I tried 21/2/18 for some time now, being moderately happy, but not quite enjoying the balance of guard v burst/dps.
List of differences against 21/2/18
You get:
+30% crit dmg on HiB
30 second reduced CD on Recharge cells
+6% dmg on HiB, Stockstrike, Hammer shot under most normal circumstances (IR is applied)
You lose
Immobilisation with stealth scan and harpoon (Without the -10sec cooldown reduction on harpoon, this talent loses power through lack of application)
25% dmg on ion cell and shock duration reduced by 3 seconds (It feels marginal whenever I use it)
Storm an Undoubtedly big loss, and one which is very difficult to lose. Another interrupt, and a gap closer is hard to give up.
2/3 Rain of fire or 2/3 Focused Impact?
(I have not tested this out yet, but any feedback with the 22 points in Assault in mind would be most welcome)